WO2019053669A2

WO2019053669A2 - Electrical motor arrangement for electrical vehicles

Info

Publication number: WO2019053669A2
Application number: PCT/IB2018/057107
Authority: WO
Inventors: Albert Lam
Original assignee: Detroit Electric Ev Technologies (Zhejiang) Limited
Priority date: 2017-09-15
Filing date: 2018-09-17
Publication date: 2019-03-21
Also published as: GB201714896D0; WO2019053669A3; GB2559441A

Abstract

Disclosed is an electrical motor arrangement for an electrical vehicle. The electrical motor arrangement includes at least one electrical motor. The at least one electrical motor includes a casing, a stator mounted on casing, a rotor including a rotor shaft and magnetic bearings coupled to ends of rotor shaft. The stator includes one or more radial plate-like stator elements extending from the casing, wherein each of the stator elements includes a central hole. The rotor shaft is disposed within the central hole of each of the one or more plate-like stator elements. The rotor includes one or more radial plate-like rotor elements attached to rotor shaft. Moreover, principal planes of one or more radial plate-like stator and rotor elements are arranged mutually to abut with a magnetic separation gap therebetween, and one or more radial plate-like stator and rotor elements are arranged to have electrical winding coil arrangements disposed thereon. Optionally, alternatively, the at least one electrical motor is implemented so that its rotor encircles its stator, wherein the stator is centrally implemented within the at least one electrical motor.

Description

ELECTRI CAL MOTOR ARRAN GEM ENT FOR ELECTRI CAL

V EH I CLES

TECH N I CAL Fl ELD The present disclosure relates generally to electrical motor arrangements; more specifically, the present disclosure relates to electrical motor arrangements for electrical vehicles.

BACKGROU N D Recently, vehicles have become an integral part of everyday life. Such vehicles, and specifically automobiles, have introduced convenience and comfort when addressing daily transportation needs. Contemporarily, automobiles are capable of traversing distances of several hundred miles or kilometres within relatively short periods of time, for example within hours. With advancements in automobile technology, there has recently been an increase in interest for electrical vehicles, for example to address pollution issues in large cities and to try to move humanity towards a more sustainable future in terms of utilization of Earth's resources. Presently, there are consumed 80 million barrels of oil per day to keep industrial civilization functioning; a significant portion of such consumption is utilized for transporting goods and people.

Thus, electrical vehicles are potentially capable of playing a significant role in reducing environmental pollution and encouraging sustainable technologies. Typically, the electrical vehicles produce fewer byproducts that cause anthropogenic climate change in comparison to conventional vehicles powered by fossil fuels; the electrical vehicles are susceptible to being provided with power from renewable energy sources such as solar panels, wind turbines, tidal power generation arrangements, ocean wave power, geothermal energy and so forth. However, it has been appreciated that electrical vehicles of superlative performance have to be manufactured to encourage people to use electrical vehicles instead of corresponding- performance internal combustion engine vehicles.

Generally, contemporary electrical vehicles include high performance vehicles which utilize large motor arrangements and provide brisk accelerations when in operation. Usually, such motor arrangements are known to include one or more electrical motors. Such an electric motor incudes a stator and/or rotor that employ permanent magnets. Such use of permanent magnets leads to a large and heavy design of the motor. Furthermore, in order to provide high performance (such as high torque using the motor arrangement), the permanent magnets may include powerful rare-earth magnets. It will be appreciated that using such rare earth magnets leads to high manufacturing costs associated with the motor arrangements and consequently, high manufacturing costs associated with corresponding electrical vehicles including such motor arrangements. Furthermore, in operation of the aforesaid electrical motor, one or more moving components thereof (for example, a rotor thereof) may be subjected to physical contact between one or more stationary components of the aforesaid electrical motor (for example, a stator thereof). It will be appreciated that during a high rate of rotation of the aforesaid electrical motor and/or long periods of operation of aforesaid electrical motor, such physical contact may increase wear and tear within the aforesaid electrical motor, thereby leading to a shorter operating life thereof. Additionally, to reduce a size of the electrical motor, a magnetic clearance gap that is included between various components of the electric motor is reduced. In high speed operation of the electrical vehicle, heat is generated in the electrical motor, for example due to resistance (or drag) between the one or more moving components of the electrical motor and air within the electrical motor, and/or resistive electrical power dissipation within the electrical motor. Dissipating such heat generated within the electrical motor can potentially represent a severe technical problem, for example when the electrical motor is implemented in a compact format.

Therefore, in light of the foregoing discussion, there is a need to overcome the aforementioned drawbacks associated with conventional motor arrangements employed in electrical vehicles. High-performance compact digital motors are known for use in portable electrical appliances, for example portable vacuum cleaners and hair driers. Such compact digital motors are described, for example, in a published patent document WO2010/112930 A2 (^High-speed electric system", applicant - Dyson Technology Ltd ., UK) . These high-performance compact digital motors employ rare- earth permanent magnets.

SU M MARY

The present disclosure seeks to provide an improved electrical motor arrangement for an electrical vehicle, wherein the electrical motor arrangement includes at least one electrical motor.

According to a first aspect, an embodiment of the present disclosure provides an electrical motor arrangement for an electrical vehicle, the electrical motor arrangement including at least one electrical motor, characterized in that the at least one electrical motor includes:

- a casing;

- a stator mounted on the casing, the stator including one or more planar stator elements extending from the casing, wherein each of the one or more planar stator elements includes a central hole therein; and

- a rotor including

- a rotor shaft that is disposed within the central hole of each of the one or more planar stator elements of the stator; and

- one or more planar rotor elements attached to the rotor shaft; wherein principal planes of the one or more planar stator and rotor elements are arranged mutually to abut with a magnetic separation gap therebetween, and the one or more planar stator elements and the one or more planar rotor elements are arranged to have electrical winding coil arrangements disposed thereon; and

- a bearing arrangement that rotationally supports the rotor relative to the stator.

Optionally, the bearing arrangement includes a magnetic bearing arrangement for providing non-contact rotation of the rotor relative to the stator.

Optionally, the one or more planar elements of the rotor and the stator are implemented as radial plate-like elements having a circular periphery. The present disclosure seeks to provide an efficient electrical motor arrangement for an electrical vehicle; moreover, the electrical motor arrangement is capable of being fabricated inexpensively, in a lightweight and compact format, wherein the electrical motor arrangement is capable of improving performance of an electrical vehicle when utilized therein.

It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.

The present invention is included in the general business context, which aims to substitute vehicles powered by traditional fuels, for example gasoline or diesel, by electric vehicles. In particular, the present invention is intended for use in electric vehicles used within cities, which can be highly beneficial to the local environment due to significant reduction of gaseous emissions as well as significant reduction of noise. Overall environmental benefits can also be significant when electric vehicles are charged from renewable energy sources.

DESCRI PTI ON OF THE DRAW I NGS

The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.

Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein :

FIG. 1 is a schematic illustration of an electrical motor arrangement for an electrical vehicle, wherein the electrical motor arrangement includes at least one electrical motor, in accordance with an embodiment of the present disclosure;

FIG. 2 is a top-view of a planar stator element, for example implemented as a radial plate-like element having a circular periphery, within a casing of the at least one electrical motor FIG. 1, in accordance with an embodiment of the present disclosure;

FIG. 3 is a top-view of the planar rotor element of FIG. 1, for example implemented as a plate-like element having a circular periphery, in accordance with an embodiment of the present disclosure; and

FIG. 4 is a circuit configuration of electrical circuit implemented for operation of the at least one electrical motor (such as the at least one electrical motor of FIG. 1), in accordance with an embodiment of the present disclosure.

In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non- underlined number to the item . When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

D ESCRI PTI ON OF EM BOD I M EN TS

In overview, embodiments of the present disclosure are concerned with improved electrical motor arrangements for electrical vehicles.

Referring to FIG. 1, there is shown a schematic illustration of an electrical motor 1 00 , for example for including in a motor arrangement of an electrical vehicle, in accordance with an embodiment of the present disclosure. The electrical motor 1 00 includes a casing 1 02 . The casing 1 02 is operable, namely configured, to accommodate one or more components (as described herein later) of the electrical motor 1 00 therein. In one example, the casing 1 02 is implemented as a hollow cylindrical structure that is operable to accommodate the one or more components of the electrical motor 1 00 . In another example, the casing 1 02 is implemented as a hollow cylindrical structure including a plurality of parts, for example two semi-cylindrical parts, alternatively for example four quadrant parts. In such an instance, the semi- cylindrical parts are operable, namely configured, to abut, when assembled, along surfaces thereof, to form the casing 1 02 . It will be appreciated that such an implementation of the casing 1 02 including the plurality of parts enables convenient assembly (and/or disassembly) of the electrical motor 1 00 .

For example, the one or more components of the electrical motor 1 00 are assembled together and, subsequently, enclosed within the casing 1 02 thereon. In an example, the casing 1 02 is fabricated from a metallic material, for example from one or more profiled and pressed metal sheets, from one or more castings or from one or more machined component. The metallic material employed for the casing 1 02 includes, for example, at least one of: Aluminium, Titanium, steel, Copper, metal alloy. In an example, there is used Aluminum sheet for fabricating the casing 1 02 . Such fabrication of the casing 1 02 using the Aluminium sheet allows a lightweight casing structure to be fabricated with a low associated manufacturing cost. Additionally, using the Aluminum sheet for fabricating the casing 1 02 enables convenient dissipation of heat generated during operation of the electrical motor 1 00 . In another example, the casing 1 02 is fabricated using a steel sheet, for example as aforementioned. Optionally, the casing 1 02 includes an exterior cavity through which a cooling fluid, for example force air cooling, can be flowed when the one electrical motor 1 00 is in operation .

Furthermore, the electrical motor 1 00 includes a stator 1 04 mounted onto an interior of the casing 1 02 . The stator 1 04 is a stationary component of the electrical motor 1 00 . Furthermore, the stator 1 04 is operable to provide a magnetic field to enable operation of one or more rotatable components (such as a rotor) of the electrical motor 1 00 . The stator 1 04 includes one or more planar stator elements 1 04 A- B, for example the one or more stator elements 1 04 A- B are implemented as one or more plate-like radial elements each having a circular periphery and a central hole therein, extending from the casing 1 02 , wherein each of the one or more planar stator elements 1 04A- B includes a central hole 1 06 . Optionally, principal planes of the one or more planar stator elements 1 04 A- B are arranged to be substantially orthogonal to a central axis of rotation of a rotor of the electrical motor 1 00 . By "substantially orthogonal" is meant in a range of +45° to + 135°, more optionally in a range of 70° to 110°, and yet more optionally in a range of 80° to 100°. In one example, the one or more planar stator elements 1 04 A- B are fabricated to include a highly paramagnetic material, for example a ferromagnetic material, for example, a ferrite material or a ferromagnetic laminate structure, are optionally reinforced using at least one of: fiberglass (fibreglass), Carbon fiber (Carbon fibre), an electrically insulating material including an organic binding resin . Beneficially, although the one or more planar stator elements 1 04A- B are fabricated a highly paramagnetic material, the one or more planar stator elements 1 04A- B exhibit a low electrical conductivity in order to reduce eddy currents generation therein when subjected to a temporally changing magnetic field in operation . Furthermore, the one or more planar stator elements 1 04 A- B, for example implemented radial plate-like elements having a circular periphery, are attached to an inside of the casing 1 02 , as aforementioned . In one example, the one or more planar stator elements 1 04A- B are implemented in a plurality of parts, for example as semi-circular half plates that are operable to be arranged to form the one or more planar stator elements 1 04A- B . For example, the casing 1 02 is implemented as a semi-cylindrical structure. In such an instance, the one or more planar stator elements 1 04 A- B including semi-circular half plates are formed as an integral part of the plurality of semi- cylindrical structures of the casing 1 02 . Such an implementation of the one or more planar stator elements 1 04A- B enables easy assembly and disassembly of one or more components of the electrical motor 1 00 . Additionally, the one or more planar stator elements 1 04 A- B includes a central hole 1 06 that enables one or more components (such as a rotor shaft) of the electrical motor 1 00 to be accommodated therein when the electrical motor 1 00 is in an assembled state. Moreover, the electrical motor 1 00 includes a rotor 1 08 . The rotor 1 08 is a rotatable component of the electrical motor 1 00 . The rotor

I 08 is rotatably mounted relative to the stator 1 04 , and is operable in cooperation with the stator 1 04 to provide rotational mechanical power for rotating one or more wheels of the electrical vehicle. In an embodiment, the rotor 1 08 is operable to rotate at a maximum rotation rate in a range of 30000 rotations per minute (r.p.m.) (or 3141.59265 radians per second) to 100000 rotations per minute (r.p.m.) (or 10471.975 radians per second). It will be appreciated that such a high rotation rate of the rotor 1 08 enables the electrical motor 1 00 to be constructed in a relatively light-weight and compact format, and yet able to output considerable rotation mechanical power; for example, the electrical motor 1 00 is susceptible to being manufactured to provide a rotational mechanical output power of 100 kW and weigh in a range of 3 kg to 10 kg, to have the casing 1 02 having a diameter in a range of 20 cm to 40 cm, and to have the casing 1 02 having a length in a range of 25 cm to 50 cm. The rotor 1 08 includes a rotor shaft 1 1 0 that is disposed in operation within the central hole 1 06 of each of the one or more planar stator elements 1 04A- B of the stator 1 04 . For example, the rotor shaft

I I 0 is implemented as a cylindrical structure, for example with a solid cross-section or a hollow cross-section (to reduce weight), that is operable to rotate around an elongate axis of the rotor shaft 1 1 0 . Furthermore, the rotor 1 08 includes one or more planar rotor elements 1 08A- B attached to the rotor shaft 1 1 0 ; optionally, the one or more planar rotor element 1 08A- B are implemented as one or more radial plate-like elements having a circular periphery. In one example, the one or more planar rotor elements 1 08A- B are fabricated to include a highly paramagnetic material, for example a ferrite material or a laminate ferromagnetic material (for example, laminate Silicon steel sheet). Beneficially, the one or more planar rotor elements 108A-B are reinforced using fiberglass (fibreglass), Carbon fiber (Carbon fibre) or similar. The one or more planar rotor elements 108A-B are fabricated from a material that exhibits a low electrical conductivity in order reduce eddy correct effects when the one or more planar rotor elements 108A-B are subjected to temporally changing magnetic fields when in operation. Furthermore, the one or more planar rotor elements 108 A- B are attached to the rotor shaft 110 along an elongate axis thereof. The one or more planar rotor elements 108A-B are arranged so that their principal planes are substantially orthogonal to the rotor shaft 110; by "substantially orthogonal" is meant in a range of +45° to +135°, more optionally in a range of 70° to 110°, and yet more optionally in a range of 80° to 100°. Optionally, the one or more planar rotor elements 108A-B are tapered as a function of radial distance from the elongate axis of the rotor shaft 110, wherein the one or more planar rotor elements 108A-B are thicker where they are adjoined to the rotor shaft 110 and thinner at their distal circumferential edge remote from the rotor shaft 110. There is beneficially employ for the one or more planar rotor elements 108A-B a tapering angle in a range of 0.5° to 5° for an exposed principal planar surface of the one or more planar rotor elements 108A-B and an orthogonal radial direction from the elongate axis of the rotor shaft 110; the one or more planar stator elements 104A-B are then correspondingly inversely tapered such that they are thicker where they adjoin to the casing 102 and thinner at their distal edge remote from the casing 102, such that a uniform gap is provided between external surface of the one or more stator elements 104 A- B and their corresponding one of more planar rotor elements 108 A- B. Furthermore, in operation, heat may be generated in the electrical motor 1 00 , for example due to resistance (or drag) of the rotating rotor 1 08 against air within the electrical motor 1 00 , flow of electrical current through one or more components of the electrical motor 1 00 , and so forth. In such an instance, providing one or more planar stator elements 1 04A- B, for example one or more radial plate-like elements as aforementioned, and the one or more planar rotor elements 1 08A- B, for example one or more radial plate-like elements as aforementioned, enables improved air flow (such as, between the one or more planar stator and rotor elements) within the electrical motor 1 00 for heat transfer purposes, namely cooling purposes. Consequently, the improved air flow within the electrical motor 1 00 makes it practical for the electrical motor 1 00 to be air cooled, thereby, reducing a requirement of external cooling arrangements to be accommodated therein . It will be appreciated that such air cooling of the electrical motor 1 00 can be arranged in a lightweight and compact design and furthermore, will be associated with a lower manufacturing cost (due to reduced costs associated with cooling arrangements). Additionally, such air cooling enables a high speed operation of the electrical motor 1 00 to be achieved, to achieve a high mechanical output power from the electrical motor 1 00 relative to its physical size.

Moreover, principal planes of the one or more planar stator elements 1 04A- B and rotor elements 1 08 A- B are arranged mutually to abut with a magnetic separation gap 1 1 2 therebetween, as aforementioned, to allow the rotor 1 08 to rotate relative to the stator 1 04 . For example, the one or more planar rotor elements 1 08 A- B, for example one or more radial plate-like elements as aforementioned, are attached to the rotor shaft 110 such that the one or more planar rotor elements 108 A- B are positioned alternately with the one or more planar stator elements 104A-B of the stator 104, for example as illustrated in FIG. 1. In such an instance, it will be appreciated that the one or more planar stator elements 104 A- B do not obstruct the rotation of the rotor 108 as the one or more planar rotor elements 108 A- B of the rotor 108 are disposed in a gap formed by two adjacent planar stator elements 104A-B. Furthermore, such an arrangement of the one or more planar stator elements 104A-B and the one or more planar rotor elements 108A- B enables formation of the aforementioned magnetic separation gap 112 therebetween. For example, the magnetic separation gap 112 is defined by a distance between surface principal planes of the one or more radial planar stator elements 104A-B and surface principal planes of the one or more planar rotor elements 108A-B (such as, for example, surface planes of the one or more planar stator elements 104A-B and surface planes of the one or more planar stator elements 108A-B facing each other, for example as illustrated in FIG. 1). According to an embodiment, the magnetic separation gap 112 is in a range of 0.1 mm to 10.0 mm, more optionally in a range of 0.3 mm to 5.0 mm and yet more optionally substantially 0.9 mm; "substantially" here pertains to an order of +/- 25% variation. In one example, the magnetic separation gap 112 is substantially 1.0 mm. In another example, the magnetic separation gap is substantially 4.5 mm.

Moreover, the one or more planar stator elements 104A-B and the one or more planar rotor elements 108A-B are arranged to have electrical winding coil arrangements disposed thereon. In one example, the one or more planar stator elements 104A-B are arranged to have electrical winding coil arrangements 1 1 4A- B disposed thereon . Such electrical winding coil arrangements 1 1 4A- B enable there to be provided a stator magnetic field that interacts with a rotor magnetic field generated by the rotor 108 to enable a torque to be generated by the electrical motor 1 00 . In an embodiment, the electrical winding coil arrangements 1 1 4 A- B are implemented using printed circuit board conductive tracks; for example, a printed circuit board is utilized having conductive tracks that are electro-plated to increase their thickness after lithography to enable them to handle more current, for example currents approaching, at least momentarily, 100 Amperes. Optionally, the printed circuit board conductive tracks are implemented in a multilayer circuit board arrangement to allow more windings to be accommodated in a very limited volume of the one or more planar stator elements 1 08A- B . A similar manner of providing windings pertains also to the rotor 1 08 ; in operation, the rotor 1 08 is provided with a magnetizing current by using wireless resonant inductive power coupling from the stator 1 04 , wherein the rotor 1 08 includes thereon a rectifying arrangement, for example implemented using Silicon PN diodes, Silicon Carbide diodes or Schottky junction diodes, for rectifying inductively coupled power received at the rotor 1 08 into DC (direct current) magnetizing current for windings of the rotor 1 08 , disposed on the one or more planar rotor elements 1 08 A- B of the rotor 1 08 . Examples of such an implementation will be described in greater detail later.

For example, the one or more planar stator elements 1 04 A- B are implemented as printed circuit boards that are fabricated using fiberglass (fibreglass) . In such an instance, the electrical winding coil arrangements 1 1 4 A- B are implemented as copper conductive tracks that are lithographically (for example, using optical lithography) printed on the printed circuit boards; alternatively, a lithographically- defined etching process is employed to define the winding coil arrangements 1 1 4 A- B . Furthermore, such conductive tracks associated with the one or more planar stator elements 1 04 A- B enable a flow of electrical current therethrough. Such a flow of electrical current through the conductive tracks enables the stator 1 04 to function as an electromagnet for providing the magnetic field for generating a torque to rotate the rotor 1 08 . In an embodiment, the electrical motor 1 00 includes non-permanent- magnet ferrite elements for defining a torque-generating magnetic field for the electrical motor 1 00 when in operation, as aforementioned . In one example, the non-permanent-magnet ferrite elements are implemented as unmagnetized ferrite cores within the one or more planar stator elements 1 04 A- B . In one example, each of the one or more planar stator elements 1 04 A- B are implemented as a plurality of layers that are arranged to form the one or more planar stator elements 1 04A- B; for example, layers of ferrite ceramic or Silicon steel transformer plates are interposed alternately between fiberglass support layers, wherein the fiberglass support layers are insulating to reduce eddy current losses and provide for a robust mechanical structure to be achieved. In such an instance, the unmagnetized ferrite cores are implemented as a ferromagnetic ferrite planar element that is incorporated (or "sandwiched") between layers comprising each of the one or more planar stator elements 1 04A- B . In one example, the ferromagnetic planar element is fabricated using Silicon steel, for example sheets of silicon steel as conventionally employed in laminated transformer cores. In another example, the planar element has a thickness in a range of 100 micrometers (μηι) to 3000 micrometers (μηι), more optionally in a range of 250 micrometers ( m) to 2000 micrometers ( m). In such an instance, the unmagnetized cores enable there to be provided a low magnetic reluctance path for the magnetic field associated with the stator 1 04 . Furthermore, it will be appreciated that the magnetic field is provided substantially orthogonally to the principal planes of the one or more planar stator and rotor elements. According to an embodiment, the unmagnetized cores, for example ferrite cores, have a relative permeability (μ_Γ) in a range of 10 to 3000 and more optionally, in a range of 100 to 1000. In one example, the unmagnetized cores are fabricated from iron alloy powder, by using a technique such as powder sintering. In such an instance, an electrical conductivity associated with the unmagnetized forrito cores is low as compared to the relative permeability thereof, to reduce magnetic hysteresis associated with the provided magnetic field and/or to reduce induced eddy currents associated with electrical power provided to the electrical winding coil arrangements 1 1 4 A- B .

In an example, the one or more planar rotor elements 1 08 A- B are arranged to have electrical winding coil arrangements 1 1 6A- B disposed thereon . According to an embodiment, the electrical winding coil arrangements 1 1 6 A- B are implemented using printed circuit board conductive tracks, for example as described in the foregoing . For example, the one or more planar rotor elements 1 08 A- B are implemented as printed circuit boards that are fabricated using fiberglass (fibreglass) substrates. In such an instance, the electrical winding coil arrangements 1 1 6A- B are implemented as conductive tracks that are lithographically printed on the printed circuit board; alternatively, the conductive tracks are produced using a lithographically-defined etching process. In one example, the printed circuit board includes copper conductive tracks.

In an example embodiment, the electrical motor 1 00 includes a mechanical bearing arrangement for rotationally supporting the rotor shaft 1 1 0 relative to the stator 1 04 and the casing 1 02 . Alternatively, the electrical motor 1 00 includes a magnetic bearing arrangement, for example implement by magnetic bearings 1 1 8A- B coupled to ends of the rotor shaft 1 1 0 , for rotationally supporting the rotor shaft 1 1 0 relative to the stator 1 04 . Yet alternatively, the electrical motor 1 00 optionally includes a combination of the magnetic bearing arrangement and the mechanical bearing arrangement for rotationally supporting the rotor shaft 1 1 0 relative to the stator 1 04 . Optionally, the mechanical bearing arrangement provides support only when the electrical motor 1 00 is delivering considerable mechanical power, for example in excess of 10 kW mechanical power, otherwise the magnetic bearing arrangement provides support.

For example, the rotor 1 08 is beneficially operable to rotate up to high rotation rates, such as up to rotation rates in a range of 30000 rotations per minute (r.p.m .) (or 3141.59265 radians per second) to 100000 rotations per minute (r.p. m .) (or 10471.975 radians per second) . In such an instance, the magnetic bearing arrangement is operable to prevent physical contact between the rotor shaft 1 1 0 and one or more other components of the electrical motor 1 00 , such as, for example, the one or more planar stator elements 1 04 A- B . The magnetic bearing arrangement is operable to restrain the rotor shaft 1 1 0 relative to an axial direction parallel to an elongate axis of the rotor shaft 1 1 0 , but to allow for the rotor shaft 1 1 0 to rotate freely relative to the stator 1 04 . The magnetic bearing arrangement is beneficially implemented using permanent magnets, for example using rare-earth permanent magnets, or is implemented using electromagnets, or using a combination of permanent magnets and electromagnets. Optionally, the electromagnets are only energized when the electrical motor 1 00 is under heavy load during operation, for example delivering more than 10 kW mechanical power.

As shown, the magnetic bearings 1 1 8 A- B include rings that are coupled to the rotor shaft 1 1 0 at two ends thereof. Furthermore, the magnetic bearings 1 1 8 A- B include rings that are coupled to the stator 1 04 opposite to the rings coupled to the rotor shaft 1 1 0 . In such an instance, the rings coupled to the rotor shaft 1 1 0 and the rings coupled to the stator 1 04 are associated with same magnetic poles (such as magnetic north poles or magnetic south poles). It will be appreciated that providing such same magnetic poles on the magnetic bearings 1 1 8 A- B enables to maintain a gap between the rotor 1 08 and the stator 1 04 using magnetic levitation (such as, by magnetic repulsion therebetween). In an embodiment, the magnetic bearings 1 1 8A- B include one or more permanent magnets, as aforementioned. For example, the magnetic bearings 1 1 8 A- B includes one or more rare-earth magnets. In one example, the one or more rare-earth magnets are neodymium rare-earth magnets.

According to one embodiment, the rotor 1 08 of the electrical motor 1 00 is further provided with mechanical bearings 1 20 A- B that bears the rotor 1 08 relative to the stator 1 04 when the magnetic bearings 1 1 8A- B are loaded to cause at least a portion of a gap of the magnetic bearings 1 1 8 A- B to be mechanically contacted. For example, at a high speed operation of the electrical motor 1 00 due to the high rotation rate of the rotor 1 08 , a load on the rotor shaft 1 1 0 increases. Consequently, a load associated with the magnetic bearings 1 1 8A- B increases. In such an instance, the gap between the rotor 1 08 and the stator 1 04 decreases, leading to a "bottoming out" condition of the magnetic bearings 1 1 8 A- B (such as a condition associated with physical contact of the rings coupled to the rotor shaft 1 1 0 and the stator 1 04 respectively). In such an instance, the mechanical bearings 1 20 A- B enable to reduce friction associated with the physical contact of the rings of the magnetic bearings 1 1 8 A- B. In one example, the mechanical bearings 1 20 A- B include a ball- race bearing arrangement. In such an instance, rotation of the rotor 1 08 is supported by rolling of a plurality of balls on races associated with the ball-race bearing arrangement. In another example, the mechanical bearings 1 20A- B include a roller-race bearing arrangement. In such an instance, rotation of the rotor 1 08 is supported by rolling of a plurality of rollers on races associated with the roller-race bearing arrangement.

In one embodiment, the electrical motor 1 00 includes a plurality of ferrite spacer rings 1 22A- B . For example, the ferrite spacer rings 1 22A- B are arranged between the one or more planar stator elements 1 04 A- B . In such an instance, the plurality of ferrite spacer rings 1 22A- B further enables to provide the magnetic field substantially orthogonally to the principal planes of the one or more planar stator elements 1 04 A- B and the one or more planar rotor elements 1 08 A- B .

Referring to FIG. 2, there is shown a top-view of the planar stator element 1 04A within the casing 1 02 of FIG. 1, in accordance with an embodiment of the present disclosure. As shown, the planar stator element 1 04 A is optionally implemented as semi-circular half plates 202 A- B . Furthermore, each half-plate includes electrical winding coil arrangements 1 1 4A- B implemented as phase coils PI, P2 and P3. As shown, the phase coils PI, P2 and P3 are disposed in a 3-phase arrangement and at a sector angle of 180°, namely 60° per phase P, such that each semi-circular half plates 202 A- B includes the phase coils PI, P2 and P3 associated with the 3-phases. In one example, the phase coils PI, P2 and P3 are disposed at a sector angle of 90°, namely 30° per phase P. In another example, each of the phase coils PI, P2 and P3 are formed at an angle of 60° . In yet another example, each of the phase coils PI, P2 and P3 is associated with multiple turns of conductive tracks thereon . Moreover, the planar stator element 1 04A includes the central hole 1 06 for accommodating the rotor shaft 1 1 0 therein .

Referring to FIG. 3, there is shown a top-view of the planar rotor element 1 08 A of FIG. 1, in accordance with an embodiment of the present disclosure. As shown, the planar rotor element 1 08 A is attached to the rotor shaft 1 1 0 ; the planar rotor element 1 08 A is implemented as a radial plate-like element having a circular distal peripheral edge. Furthermore, the planar rotor element 1 08A includes electrical winding coil arrangements 1 1 6 A- B implemented as winding coils C. As shown, the winding coils C are formed at an angle of 60° and moreover, the winding coils C are disposed at a sector angle of 180° on the planar rotor element 1 08 A. In one example, the winding coils C are disposed at a sector angle of 90° on the radial plate-like rotor element 1 08 A. In another example, each of the winding coils C is associated with multiple turns of conductive tracks thereon .

In one embodiment, the one or more planar rotor elements 1 08A includes a peripheral edge reinforcement arrangement 302 for converting radial forces acting upon the rotor 1 08 when rotating in operation into corresponding circumferential forces. For example, during high speed operation of the at least one electrical motor 1 00 , the one or more planar rotor elements 1 08A- B experience large centrifugal forces due to a high rotation rate of the rotor 1 08 , for example as aforementioned with maximum rotation rates in a range of 30000 r.p.m . (or 3141.59265 radians per second) to 100000 r.p.m . (or 10471.975 radians per second). It will be appreciated that such large centrifugal forces may lead to damage of the one or more planar rotor elements 1 08A. In such an instance, the peripheral edge reinforcement arrangement 302 is operable to substantially absorb the centrifugal forces experienced by the one or more planar rotor elements 1 08A- B, converting such centrifugal forces to peripheral circumferential forces, thereby, preventing damage to the one or more planar rotor elements 1 08 A- B. In an example, the rotor 1 08 and/or the stator 1 04 only each include a single planar element thereon; alternatively, the rotor 1 08 and/or the stator 1 04 each include a plurality of planar elements thereon. According to an embodiment, the peripheral edge reinforcement arrangement 302 includes a carbon fiber ring. For example, the carbon fiber ring is associated with a same thickness as a thickness of the one or more planar rotor elements 1 08 A- B at their distal peripheral edge. In such an instance, the carbon fiber ring is arranged around the peripheral edge of the one or more planar rotor elements 1 08 A- B. According to another embodiment, the peripheral edge reinforcement arrangement 302 includes a ceramic ring. Referring to FIG. 4, there is shown a circuit configuration of an electrical circuit 400 implemented for operation of the electrical motor (such as the electrical motor 1 00 of FIG. 1), in accordance with an embodiment of the present disclosure. As shown, the electrical circuit 400 includes a battery arrangement 402 , for example a 400 Volt battery unit having a storage capacity of 200 Ampere-hours. Furthermore, the electrical circuit 400 includes a rotor excitation unit 404 for transferring power using a resonant inductive power coupling arrangement 406 . The resonant inductive power coupling arrangement 406 is operable to provide electrical power to the rotor 408 (such as the rotor 1 08 of FIG. 1) using resonant inductive power coupling. Subsequently, a current return of the rotor excitation unit 404 is directed to a negative terminal of the battery arrangement 402 via a stator 41 0 (such as the stator 1 04 of FIG. 1) . Such an arrangement is slightly akin to a known series-coupled electrical motor. The resonant inductive power coupling arrangement 406 is operable to function at a resonant frequency in a range of 50 kHz to 1 MHz, more optionally at a resonant frequency in a range of 100 kHz to 300 kHz. In an embodiment, the battery arrangement 402 includes Lithium Iron Phosphate (Li FeP04) gel polymer cells.

In an embodiment, the rotor 408 includes a rectifier arrangement 41 2 for converting resonant inductively coupled power received at the rotor 408 into direct current (DC) to generate the rotor magnetic field . For example, the resonant inductive power coupling arrangement 406 is operable to transfer alternating current (AC) to the rotor 408 . Subsequently, the rectifier arrangement 41 2 is operable to convert the transferred alternating current to direct current. In an example, the rectifier arrangement 41 2 includes a bridge rectifier arrangement. Furthermore, the rectifier arrangement 41 2 provides the converted direct current to the electrical winding coil arrangements 41 4 , disposed on one or more planar rotor elements of the rotor 408 (such as the one or more planar rotor elements 1 08A- B of the rotor 1 08 of FIG. 1, as described in the foregoing). Consequently, flow of the converted direct current through the electrical winding coil arrangements 41 4 enables to generate a magnetic field of the rotor 408 . The magnetic field of the rotor 408 interacts in operation with a magnetic field of a corresponding stator to generate torque, wherein the magnetic field of the stator is commutated to define a rate of rotation of the rotor 408 . Moreover, in operation the magnetic field of the stator is commutated in a "digital" manner, for example as described in the earlier patent document WO2010/112930 A2 ^High-speed electric system", applicant - Dyson Technology Ltd., UK), that is hereby incorporated by reference. In such a manner of operation, phases PI, P2 and P3 of the stator are excited by current pulses, namely in a commutated manner, with non-excited periods therebetween to allow the rotor 408 to freewheel during the non-excited periods. Optionally, the pulses are pulse-width-modulated (PWM) controlled to control a torque generated by the electrical motor 1 00 , and rate of commutation of the phases PI, P2 and P3 is used to control a rate of rotation of the rotor 408 . It will be appreciated that the electrical motor 1 00 is optionally operated in a slippage manner of operation wherein the rotor 408 lags a rate of commutation o the phases PI, P2 and P3. However, it will be appreciated that the electrical motor 1 00 is not limited to three phases, and can optionally be implemented with other numbers of phases, for four-phase, five- phase and so forth, even potentially two-phase. In an embodiment, the stator 41 0 is provided with a silicon carbide transistor switching arrangement 41 6 for switching commutation magnetizing currents supplied to the stator 41 0 when in operation : silicon carbide transistors are highly beneficial because devices can be bought commercially at modest cost that can switch 100's of Amperes current within nanoseconds. However, it will be appreciated that other types of switching devices are optionally employed, for example FET's, bipolar transistors, D-MOS FET transistors and so forth . As shown, the stator 41 0 includes a three-phase arrangement including phase coils PI, P2, P3 and the switching arrangement 41 6 . Furthermore, the switching arrangement 41 6 includes switching elements S I, S2, S3. Moreover, a negative connection of the rotor excitation unit 404 is coupled via the phase coils PI, P2, P3 and their respective switches SI, S2, S3 to the negative terminal of the battery arrangement 402 . Additionally, the phase coils PI, P2, P3 are associated with the electrical winding coil arrangements (such as the electrical winding coil arrangements 1 1 4 A- B of FIG. 1) disposed on the one or more planar stator elements of the stator 41 0 .

In an embodiment, the electrical motor including the rotor 408 and stator 41 0 is operable to function as a digitally-commutated electrical motor, for example in a manner as aforementioned . Specifically, digital commutation is provided to generate motion in the electrical motor 1 00 . For example, digital commutation is implemented using digitally controlled current pulses. Optionally, the rotor magnetic field is operable to interact in operation with a commutated magnetic field of a stator 41 0 of the electrical motor 1 00 . More optionally, during commutation, the current pulses are applied to commutation windings of the electrical motor 1 00 , and a free-wheeling period is implemented between application of the current pulses during which the commutation windings are non-energized. Specifically, commutation windings of the electrical motor 1 00 include an electrical winding coil arrangement disposed on the one or more planar stator elements of the stator 41 0 . Therefore, current pulses are applied to the phase coils PI, P2, P3 using the switching arrangement 41 6 , for example in a sequential commutated manner, specifically to the switching elements SI, S2, S3, respectively. In operation, a current pulse is applied to the phase coil PI of the commutation winding using the switching element SI to generate a motion in the rotor 408 . Subsequently, the current pulse is switched to phase coil P2 of commutation winding using the switching element S2 to sustain the generated motion . Furthermore, the current pulses are switched continuously from phase coils P2 to P3 and subsequently, from phase coil P3 to PI to maintain rotation of the rotor 408 . Such a commutation is implemented in a repeated manner to maintain the rotor 408 of the electrical motor 1 00 rotating in a given rotation direction . Specifically, the phase coils PI, P2 and P3 are beneficially energized in sequence as the rotor 408 rotates, and the coils PI, P2 and P3 are not energized simultaneously, namely only one commutated phase is energized at any given time. Optionally, the freewheeling period is in a range of 0.5 to 5.0 times a duration of energizing the coils PI, P2 and P3. Furthermore, the freewheeling period is implemented between the switching of current between the phase coils. Alternatively, optionally, for obtaining a smoother torque, two adjacent phase coils, for example the phase coils PI and P2, are simultaneously energized (namely, "overlapping commutation") when the winding coils C straggles significantly between phases PI and P2. Optionally, the electrical motor 1 00 is operated dynamically between such a digital manner of commutation and overlapping commutation, depending upon a rotation rate and output torque required to be delivered in operation by the electrical motor 1 00 . By employing a suitable sequence of commutation, the electrical motor 1 00 is capable of being driven in a clockwise direction of rotation as well as in an anticlockwise direction of rotation . Optionally, during commutation, current pulses are applied to the commutation windings of the at least electrical motor using pulse- width modulation (PWM) technique. Specifically, a width of the current pulses in a current-time graph may be modulated to control a speed of the at least one electrical motor and operation of the switching arrangement 41 6 . Furthermore, by using pulse-width modulation power control, a rotation rate and/or torque characteristics of the electrical motor 1 00 can be controlled very precisely, enabling the electrical vehicle to exhibit extremely smooth and versatile power transmission to wheels thereof.

Optionally, the electrical vehicle includes a motor control arrangement (not shown) to control operation of the electrical motor 1 00 described herein. It will be appreciated that the electrical vehicle optionally includes only a single electrical motor 1 00 to provide the electrical vehicle with motive power. Alternatively, it will be appreciated that the electrical vehicle includes a plurality of electrical motors 1 00 to provide the electrical vehicle with motive power, for example an electric motor 1 00 for each rear wheel . Optionally, the electrical motor 1 00 is implemented in a highly compact form as an in-hub electrical motor. It will be appreciated that the term "m otor control arrangement" used herein relates to hardware, software, firmware, or a combination of these, operable to control operation of the electrical motor 1 00 . In one embodiment, the motor control arrangement is implemented using hardware that is operable to execute a software application thereon . In one example, the software application is associated with a software application management and infotainment arrangement that is operable to control operation of the electrical motor 1 00 . Optionally, the motor control arrangement includes the rotor excitation unit 404 to couple electrical power from a battery arrangement 402 of the electrical vehicle to a resonant inductive power coupling arrangement 406 , wherefrom the electrical power is coupled to a rotor 408 of the electrical motor 1 00 for generating a rotor magnetic field. In such an instance, the rotor magnetic field is operable to interact in operation with the commutated magnetic field of the stator 41 0 of the electrical motor 1 00 . In such an instance, the rotor excitation unit 404 is operable to convert a direct current from the battery arrangement 402 into an alternating current (AC) that is coupled to the resonant inductive power coupling arrangement 406 . Furthermore, the motor control arrangement may control functioning of the switching elements SI, S2 and S3 of the switching arrangement 41 6 . Optionally, the rotor excitation unit 404 includes a resonant oscillator circuit, wherein the resonant oscillator circuit 41 8 includes a tunable capacitor 420 , a transformer 422 including a primary winding and a secondary winding, and two push-pull transistors 424 and 426 . In such an instance, the tunable capacitor 420 and the primary winding of the transformer 422 constitute a tank circuit that is tunable to a resonant frequency. Optionally, the transformer 422 is implemented as a compact ferrite core toroidal transformer. Furthermore, optionally, the two push-pull transistors 424 and 426 are driven in mutual anti-phase at the resonant frequency of the resonant oscillator circuit 41 8 . More optionally, the two push-pull transistors 424 and 426 are implemented by way of silicon carbide transistors. In one example, the switching elements SI, S2, S3 of the switching arrangement 41 0 are also implemented by way of silicon carbide transistors, for example as aforementioned. Optionally, the resonant oscillator circuit 41 8 of the rotor excitation unit 404 operates in a frequency range of 50 kilohertz to 1 megahertz, as aforementioned . In such an instance, a frequency of the alternating current that is to be coupled to the resonant inductive power coupling arrangement 406 lies within the aforesaid frequency range.

Optionally, a bypass capacitor 428 is provided across the rotor excitation unit 404 , in order to remove stray alternating current noise within the direct current provided from the battery arrangement 402 , and also to allow for a high amplitude of current pulses to be applied to the stator windings when the electrical motor 1 00 is commutation in a "digital manner" as elucidated in the foregoing. Consequently, use of such a bypass capacitor 428 allows for filtering (of noise) the direct current received by the rotor excitation unit 404 and consequently allows for filtering (of noise) the alternating current that is to be coupled to the resonant inductive power coupling arrangement 406 . The bypass capacitor 428 also allows for maintenance of the rotor magnetic field as the stator windings are digital commutated, while utilizing current from the battery arrangement 402 in a frugal efficient manner.

The electrical motor arrangement of the present disclosure includes the at least one electrical motor, as aforementioned. Furthermore, the at least one electrical motor includes the stator, the stator including one or more planar stator element, for example implemented as radial plate-like elements. Moreover, the at least one electrical motor includes the rotor, the rotor including one or more planar rotor elements, for example implemented as radial platelike elements, attached to the rotor shaft. Additionally, the one or more planar stator elements and the one or more planar rotor elements are arranged to have electrical winding coil arrangements disposed thereon. Such an arrangement of electrical coil windings on the one or more planar stator elements eliminates a requirement to include permanent magnets (such as rare-earth magnets) thereon. It will be appreciated that such elimination of requirement of permanent magnets on the stator enables the at least one electrical motor to be provided in a lightweight design and moreover, is associated with a low manufacturing cost. Furthermore, the arrangement of the at least one electrical motor including the one or more planar stator elements and rotor elements enables to provide the magnetic field substantially orthogonally, for example orthogonal, to the principal surface planes of the one or more planar stator elements and rotor elements. It will be appreciated that providing such a magnetic field enables improved concentration of the magnetic field along the one or more radial planar rotor elements. Consequently, an efficiency associated with the at least one electrical motor is increased. Moreover, implementation of the stator and the rotor using the one or more planar stator elements and rotor elements enables an improved cooling within the at least one electrical motor, for example, by allowing air flow in gaps formed between the one or more planar stator elements and rotor elements. Therefore, a requirement for the at least one electrical motor to be externally cooled is reduced, because heat is more efficiently coupled to the casing of the at least one electrical motor. Consequently, the at least one electrical motor can be made to be lightweight and compact. Furthermore, the at least one electrical motor is associated with a low manufacturing cost and also, improved power consumption due to reduced power requirement for operation of external cooling equipment. Moreover, the at least one electrical motor includes the magnetic bearings coupled to the ends of the rotor shaft. Such magnetic bearings enable wear of the at least one electrical motor to be reduced due a reduction or avoidance of physical contact of components having relative motion therebetween. Consequently, an operating life of the at least one electrical motor is increased. Therefore, it will be appreciated that the present disclosure provides a low cost, lightweight and compact motor arrangement including the at least one electrical motor, for use in an electrical vehicle. Conveniently, the at least one electrical motor is implemented as an in-hub motor. Alternatively, the at least one electrical motor is implemented as a chassis-mounted device whose rotor is coupled via flexible link to drive one or more wheels of the electrical vehicle, wherein the one or more wheels are supported on a suspension arrangement, such that the at least one electrical motor is effectively a sprung mass. In the forgoing, it will be appreciated that the stator of the at least one electrical motor circumferentially surrounds the rotor. However, in an alternative implementation, the rotor circumferentially surrounds the stator, wherein the stator is implemented along a central region of the at least one electrical motor. Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

Claims

CLAI MS

1. An electrical motor arrangement for an electrical vehicle, the electrical motor arrangement including at least one electrical motor, characterized in that the at least one electrical motor includes: - a casing;

- a stator mounted on the casing, the stator including one or more planar stator elements extending from the casing, wherein each of the one or more planar elements includes a central hole;

- a rotor including - a rotor shaft that is disposed within the central hole of each of the one or more planar stator elements of the stator; and

2. An electrical motor arrangement of claim 1, characterized in that bearing arrangement includes magnetic bearings to support the rotor shaft relative to the stator.

3. An electrical motor arrangement of claim 1, characterized in that the bearing arrangement includes a combination of magnetic bearings and mechanical bearings to support the rotor relative to the stator.

4. An electrical motor arrangement of claim 2 or 3, characterized in that the magnetic bearings are coupled to ends of the rotor shaft.

5. An electrical motor arrangement of claim 2, 3 or 4, characterized in that the magnetic bearings of the bearing arrangement include at least one permanent magnet.

6. An electrical motor arrangement of any one of claims 1 to 5, characterized in that the at least one electrical motor is operable to function as a digitally-commutated electrical motor, wherein, during commutation, current pulses are applied to commutation windings of the at least one electrical motor, and a free-wheeling period is implemented between application of the current pulses during which the commutation windings are non-energized.

7. An electrical motor arrangement of claim 6, characterized in that during commutation, current pulses are applied to the commutation windings of the at least electrical motor using pulse- width modulation (PWM).

8. An electrical motor arrangement of any one of the claims 1 to 7, characterized in that the at least one electrical motor includes non- permanent-magnet ferrite elements and/or ferromagnetic laminate elements for defining a torque-generating magnetic field for the at least one electrical motor when in operation.

9. An electrical motor arrangement of any one of the claims 1 to 8, characterized in that a resonant inductive power coupling arrangement is employed to couple electrical power to a rotor of the at least one electrical motor for generating a rotor magnetic field that is operable to interact in operation with a commutated magnetic field of a stator of the at least one electrical motor to generate output torque from the at least one electrical motor.

10. An electrical motor arrangement of claim 9, characterized in that the rotor includes a rectifier arrangement for converting resonant inductively coupled power received at the rotor into direct current to generate the rotor magnetic field.

11. An electrical motor arrangement of any one the preceding claims, characterized in that the rotor is operable to rotate at a maximum rotation rate in a range of 30000 rotations per minute (r.p.m.) (or 3141.59265 radians per second) to 100000 rotations per minute (r.p.m .) (or 10471.975 radians per second).

12. An electrical motor arrangement of claim 2 or 3, characterized in that the rotor of the at least one electrical motor is further provided with the mechanical bearings that bears the rotor relative to the stator when the magnetic bearings are loaded to cause at least a portion of a gap of the magnetic bearings to be mechanically contacted.

13. An electrical motor arrangement of any one of the preceding claims, characterized in that the magnetic separation gap is in a range of 0.1 mm to 10.0 mm .

14. An electrical motor arrangement of any one of the preceding claims, characterized in that the electrical winding coil arrangements are implemented using printed circuit board conductive tracks.

15. An electrical motor arrangement according to any one of the preceding claims, characterized in that one or more planar rotor elements include a peripheral edge reinforcement arrangement for converting radial forces acting upon the rotor when rotating in operation into corresponding circumferential forces.

16. An electrical motor arrangement of claim 15, characterized in that the peripheral edge reinforcement arrangement includes a carbon fiber ring.

17. An electrical motor arrangement of any one of the preceding claims, characterized in that the stator is provided with a silicon carbide transistor switching arrangement for switching commutation magnetizing currents supplied to the stator when in operation.

18. An electrical motor arrangement for an electrical vehicle, the electrical motor arrangement including at least one electrical motor, characterized in that the at least one electrical motor includes:

- a motor casing;

- a stator mounted centrally relative to the motor casing, the stator including one or more planar stator elements extending outwardly therefrom; and

- a rotor that encircles the stator, wherein the rotor includes

- a rotor shaft attached to a rotor casing; and

- one or more planar rotor elements attached to the rotor casing, wherein each of the one or more planar rotor elements is provided with a central hole therein for accommodating the stator; wherein principal planes of the one or more planar stator and rotor elements are arranged mutually to abut with a magnetic separation gap therebetween, and the one or more planar stator elements and the one or more planar rotor elements are arranged to have electrical winding coil arrangements disposed thereon; and a bearing arrangement that rotationally supports the rotor relative to the stator.

19. An electrical motor arrangement of claim 18, characterized in that the bearing arrangement includes magnetic bearings to support to rotor shaft relative to the stator.

20. An electrical motor arrangement of claim 18, characterized in that the bearing arrangement includes a combination of magnetic bearings and mechanical bearings to support the rotor shaft relative to the stator.

21. An electrical motor arrangement of claim 19 or 20, characterized in that the magnetic bearings are coupled to at least one end of the rotor shaft.

22. An electrical motor arrangement of any one of claims 18 to 21, characterized in that the at least one electrical motor is operable to function as a digitally-commutated electrical motor, wherein, during commutation, current pulses are applied to commutation windings of the at least one electrical motor, and a free-wheeling period is implemented between application of the current pulses during which the commutation windings are non-energized.

23. An electrical motor arrangement of claim 22, characterized in that during commutation, current pulses are applied to the commutation windings of the at least electrical motor using pulse- width modulation (PWM).

24. An electrical motor arrangement of any one of claims 18 to 23, characterized in that the at least one electrical motor includes non- permanent-magnet ferrite elements and/or ferromagnetic laminate elements for defining a torque-generating magnetic field for the at least one electrical motor when in operation.

25. An electrical motor arrangement of any one of claims 18 to 24, characterized in that a resonant inductive power coupling arrangement is employed to couple electrical power to a rotor of the at least one electrical motor for generating a rotor magnetic field that is operable to interact in operation with a commutated magnetic field of a stator of the at least one electrical motor to generate output torque from the at least one electrical motor.

26. An electrical motor arrangement of claim 25, characterized in that the rotor includes a rectifier arrangement for converting resonant inductively coupled power received at the rotor into direct current to generate the rotor magnetic field.

27. An electrical motor arrangement of any one of claims 18 to 26, characterized in that the rotor is operable to rotate at a maximum rotation rate in a range of 30000 rotations per minute (r.p.m.) (or 3141.59265 radians per second) to 100000 rotations per minute (r.p.m.) (or 10471.975 radians per second).

28. An electrical motor arrangement of claim 18, characterized in that the bearing arrangement includes magnetic bearings that include at least one permanent magnet.

29. An electrical motor arrangement to any one of claims 18 to 28, characterized in that the rotor of the at least one electrical motor is further provided with mechanical bearings that bears the rotor relative to the stator when the magnetic bearings are loaded to cause at least a portion of a gap of the magnetic bearings to be mechanically contacted.

30. An electrical motor arrangement of any one of claims 18 to 29, 5 characterized in that the magnetic separation gap is in a range of 0.1 mm to 10.0 mm .

31. An electrical motor arrangement of any one of claims 18 to 30, characterized in that the electrical winding coil arrangements are implemented using printed circuit board conductive tracks.

1 0 32. An electrical motor arrangement of any one of claims 18 to 31, characterized in that the rotor casing includes at least one peripheral edge reinforcement arrangement including a carbon fiber ring for constraining centrifugal forces acting upon the rotor casing when the at least one electrical motor is in operation.

15 33. An electrical motor arrangement of any one of claims 18 to 32, characterized in that the stator is provided with a silicon carbide transistor switching arrangement for switching commutation magnetizing currents supplied to the stator when in operation.

20